Method and apparatus for testing welding seams by ultrasound energy

ABSTRACT

A method of and apparatus for non-destructively checking by means of ultrasonic energy the material of a workpiece, especially a welding seam, in its longitudinal and in its transverse direction as to faults in the heterogenity of the material to be checked, according to which at least two ultrasonic ray bundles are simultaneously directed through a common coupling surface into the material to be checked while one of said bundles is so directed that it hits the longitudinal axis of the material to be checked at a right angle thereto whereas the other one of ray bundles is directed so as to hit said longitudinal axis at an angle of less than 90*, e.g., 45* or 60*, the sound ray bundles reflected by the respective section of the material to be checked being recorded to register possible faults of said material.

Biittcher et a1.

METHOD AND APPARATUS FOR TESTING WELDING SEAMS BY ULTRASOUND ENERGYInventors: Wolfgang Bottcher, Dortmund- Brackel; Hermann-Josef Kopineck,Dortmund-Kirchhorde; Karl-Heinz Schlusnus, Hamm; Gemot Sommerkorn,Dortmund, all of Germany lloesch Aktiengesellschaft, Dortmund, GermanyFiled: Dec. 22, 1969 Appl. N0.: 886,885

Assignee:

Foreign Application Priority Data Dec. 21, 1968 Germany ..P 18 16 255.5

US. Cl ..73/67.8 R, 73/676, 73/71.5 Int. Cl. ..G01n 24/04 Field ofSearch ..73/67.567.9, 71.5;

References Cited UNITED STATES PATENTS 4/1971 Gibbs et a1 ..73/6797/1966 Hart ..73/7l.5 9/ l 966 Stanya ..73/67.9 4/ 1967 Krautkramer..73/67.8

u51 3,685,348 1 [45] Aug. 22, 1972 FORElGN PATENTS OR APPLICATIONS1,471,333 3/1966 France ..73/67.7 1,552,533 l/1968 France ..73/67.7716,687 10/1954 Great Britain ..73/67.7 866,457 7/1958 Great Britain..73/67.7

Primary ExaminerRichard C. Queisser Assistant ExaminerArthur E. KorkoszAttorney-Walter Becker 5 7] ABSTRACT A method of and apparatus fornon-destructively checking by means of ultrasonic energy the material ofa workpiece, especially a welding seam, in its longitudinal and in itstransverse direction as to faults in the heterogenity of the material tobe checked, according to which at least two ultrasonic ray bundles areiimultaneously di re cted throfigll 5 coiiifiioii coupling surface intothe materialto be checked while oiie o f said bundles is so directedthat it hits the 1ongitudinal axis of the material to be checked at aright angle thereto whereas the other one of ray bundles is directed soas to hit said longitudinal axis at an angle of less than 90, e.g., 45or 60, the sound ray bundles reflected by the respective section of thematerial to be checked being recorded to register possible faults ofsaid material.

8 Claims, 7 Drawing Figures METHOD AND APPTUS FOR TESTING WELDWG SEAMSBY ULTRASOUND ENERGY The present invention relates to a method of andapparatus for testing a welding seam by ultrasound energy in anon-destructive manner, i. e. without destroying the welding seam. Morespecifically, the invention concerns such method and apparatus forascertaining whether the welding seam is heterogeneous with regard tothe material in the welding seam in longitudinal direction longitudinalfaults and in transverse direction transverse faults. This testing iscarried out by ultrasonic energy while employing at both sides of theseam ultrasonic probes which are guided parallel to the longitudinalaxis of the welding seam and function as emitter and/or receiver.

The non-destructive testing of linear metal formations, such as weldingseams, primarily of welded pipes with a longitudinal or helical seam bymeans of ultrasonic equipment is carried out primarily in such a waythat a pair of ultrasonic probes which is guided on both sides of thewelding seam and parallel thereto so that the equipment emits andreceives its sound impulse in a direction perpendicular to the weldingseam, and that one or more pairs of ultrasound probes are employed whichat an angle of from 45or 60emit sound ray bundles onto the welding seamor receive the same therefrom for testing the welding seam as totransverse faults.

The testing for longitudinal faults in the welding seam has become an oeration-safe method in view of the fact that it follows at'sting'inethod'according to which in two first testing cycles theright-hand or the left-hand range of the welding seam zone is tested,and that in a third testing cycl e in conformity with a throughgqnndingmethod, the proper working of the te s t i n g probes coupling to thework piece are checked. Thiiiii61s3repeated oi aft r ariother at anydesired sequence.

When testing the welding seam for transverse faults, theasb va mentionedmethod is employed whichfhowever, has the fundamental drawback that twoor four additional testing probes are to be employed which work in theabove mentioned manner, while, however, a checking of thefunctionability of these additional testing probes remains impossible."

It is, therefore, an object of the present invention to provide a methodof an apparatus for testing a welding seam or like longitudinalformation by ultrasound energy, which will overcome the above mentioneddrawbacks and will permit the testing of longitudinal and transversefaults in welding seams in the same operation-safe manner as it hasheretofore been possible exclusively with the testing for longitudinalfaults.

These and other objects and advantages of the invention will appear moreclearly from the following specification in connection with theaccompanying drawings, in which:

FIG. 1 diagrammatically illustrates in view an ultrasound head or probewith an ultrasonic transmitter sound radiating toward two sides.

FIG. 2 is a side view of the ultrasound probe of FIG. 1.

FIG. 3 diagrammatically illustrates an ultrasound head or probe with anadapter member preceding the ultrasonic vibrator.

FIG. 4 shows the ultrasound head of FIG. 3 with an adapter member.

FIG. 5 represents an ultrasound head similar to that of FIG. 3 in whichthe sound ray bundle emitted by the ultrasonic transmitter is split upinto three sound ray bundles.

FIG. 6 shows an arrangement of the ultrasound heads for the employmentof the method according to the invention.

FIG. 7 represents the monitor adjustment on the ultrasound device inconformity with the arrangement of FIG. 6.

The above outlined objects have been realized according to the presentinvention according to which each ultrasound head or probe producesultrasonic vibrations and separates the ultrasonic rays into a pluralityof sound ray bundles and emits at least two sound ray bundlessimultaneously or receives two sound ray bundles simultaneously or oneafter another. The said sgundray bundles are throygllsssessslaeliussurface introduced into the maten to be tested or r' c fi'ved t herefrom, and each ultrasound head is so guided that a sound raybundle hits perpendicularly upon the longitudinal axis of the weldingseam, whereas the other sound ray bundles intersect the longitudinalaxis of the welding seam at different angles less than Each of theultrasound heads provided for carrying out the method according to theinvention has only one ultrasonic transmitter According to a furtherfeature of the invention, the ultrasonic transmitter, which radiatessound toward both sides, is embedded in a sound-conducting'body ofsynthetic material the shape of which is so selected that I the twosound ray bundles are separated and guided in such a way that they movethrough the common coupling surface in the predetermined direction withregard to the welding seam.

With another ultrasound head equipped with an ultrasonic transmitterarranged in a well-known manner whose sound radiation toward one side isweakened by the arrangement of dampening material so that the emissionof the ultrasound energy is effected toward the other side, asound-optically acting adapter member precedes said last mentionedultrasonic transmitter, which sound radiates toward one side. The saidadapter member forms a sound-conducting body of synthetic material whichis provided with one or more cuts filled with a material which does notor only poorly conducts sound, said cuts being provided on that sidewhich faces away from the ultrasonic transmitter. That surface of saidsound-conducting body which faces toward the coupling surface extendsfrom the outside toward the center at an incline or in a polygonalmanner. It is not necessary at any rate to de-limit the split of thesound radiation caused by the shape of the adapter member, by means of azone which is not sound permeable or only poorly sound permeable such ascuts with a corresponding filling.

The adapter member has associated therewith a lead or precession chamberwhich is filled with a soundbreaking liquid confined by a sleeve.

The sound transfer to the material to be tested may be effected from thesaid chamber directly as well as from an adapter member which precedessaid chamber and conducts sound while being in conformity with thesurface of the material to be tested.

In view of the splitting up of the sound ray bundle, which has beenemitted toward one side by an ultrasound transmitter by means of opticalsteps such as mirroring and refracting, two or more sound ray bundlesare produced which in a predetermined and desired direction are conveyedto the welding seam. By correspondingly different inclinations of thesound reflecting of sound refracting surfaces of the said synthetic bodyor of the adapter member, the sound-in angle of the individual sound raybundles a to a can be selected differently so that for instance thesound ray bundle a enters the work piece with a sound-in angle (1 45while the sound ray bundle a enters the work piece to be tested at anangle (1 60 etc. By sound-in angle is meant the angle between the normalperpendicular to the surface of the material to be tested and the soundray, of the individual sound ray bundles a to a by sound focusingboundary surfaces, it is possible to obtain a desired bundling and/orspreading effect for the sound ray bundle.

Inasmuch as the separated sound ray bundles emanated from only oneultrasound transmitter pass through a common coupling surface into thewelding seam to be tested, it is possible by a known arrangement tocarry out not only a testing as to longitudinal and transverse faults inthe welding seam but at the Same qalsoatorcarry put th e function.testof the ultrasound headsthrough .a.,. Ound=through test by. means.

of the sound ray bundle directed perpendicularly onto 'the longitudinalaxis of the welding seam.

Expediently, the application of the suggested method fordestruction-free testing of welding seams according to which twoultrasound heads are employed which are guided parallel to thelongitudinal axis of the welding seam while being arranged opposite toeach other can in repeated continuous cycles be effected in such a waythat the following functions are met:

21. Testing for longitudinal faults,

b. Testing for transverse faults,

c. Coupling test.

The tests according to these functions may individually or incombination or with the exchange of the activity of the two ultrasoundheads becontrolled as working cycles. For instance, during the firstcycle, one of the two ultrasound heads emits, whereas the otherultrasound head is ineffective and through the intervention of a soundray bundle receives sound waves reflected at the longitudinal faults inthe welding seam, the signals of said sound waves being measured throughthe intervention of a monitor orifice. During the second cycle, theultrasound heads interchange their functions. With the third cycle,through the sound ray bundle directed perpendicular to the welding seam,there is effected in a manner known per se by means of the sound-throughmethod a coupling test and at the same time through further sound raybundles with the pertaining monitor orifices there are effected testsfor transverse faults, whereas during the fourth cycle the ultrasoundheads exchange their functions once more.

Referring now to the drawings in detail, an ultrasound transmitter (FIG.I) the illustrated symmetric position is not necessary and in someinstances, for instance, for energetic reasons a non-symmetric positionmay be more advantageous is embedded in a sound-conducting body ill ofsynthetic material for instance of polymethaacrylicester, and morespecifically in such a way that a sound ray bundle 12 radiates towardone side, whereas the sound ray bundle i3 radiates to the other side.The sound ray bundles i2, 13 hit upon a reflecting inclined surface M ofthe body ll which surface is so located that the reflected sound raybundles 112, 13 leave the ultrasound head 16 through a common couplingsurface 115 (FIG. 2). The sound ray bundles l2, 13 which, during atransfer from the body 11 into a work piece 117, for instance a pipe oranother bowl or plate-shaped test body, will be subjected to arefraction, have in view of the size and geometry of the body 11, beensent into two different directions which with each other confine anangle B from 0to for instance 30, 45or 60. The angle [3 is the anglebetween the sound ray bundle l2 hitting perpendicularly upon thelongitudinal axis of the welding seam l8, and the sound ray bundle 133.

FIG. 3 shows a different embodiment of an ultrasound head T9 accordingto which the ultrasonic transmitter 20 is preceded by an adapter member21 forming a sound conducting body of synthetic material. The surfacesof the adapter member 21 on the soundemitting side extend at an anglefrom the outside toward the center. A lead or precession chamber 22follows. The lateral confinement of the chamber 22 is formed by a sleeve23. For purposes of deviating the sound ray bundle, and for purposes ofthe sound coupling, the said chamber 22 is filled with a liquid forinstance water which at the border area toward the adapter member 211breaks the sound. In view of these sound optical features, theultrasound bundle 24 which emanates from the ultrasound transmitter 20is separated into the sound ray bundles 241, 242 and through theintervention of the common coupling surface 25 and at the same ordifferent sound-in angles a is introduced into the work piece 17 where afurther refraction of the two sound ray bundles 241i, 242 occurs. In thework piece 117, analogous to the sound ray bundles 112, I35 of FIG. 1,the sound ray bundle 2411 hits perpendicularly upon the welding seam,whereas the sound ray bundle 242 will then be offset at an angle B withregard to the sound ray bundle 241i and will be directed toward thewelding seam. With this ultrasonic transmitter 20, the sound radiationtoward the other side is weakened by the arrangement of dampingmaterial.

When employing ultrasound heads for work pieces, the surface of which isnot plane but is primarily arched, it is advantageous to have an adaptermember 26 of sound-conducting synthetic material precede the chamber 22(HS. 4).

In contrast to FIG. 3, the arrangement of FIG. 5 has an ultrasound head19 with an adapter member 27 which, filled with a non-sound-conductingmaterial and in view of means defining the two cuts 271, 272 filled witha non-sound-conducting material splits the sound ray bundle 24 emittedby the ultrasound vibrator 20 into three sound ray bundles 2411, 242,243 so that corresponding sound optical measures, namely the location ofthe three border surfaces, the said sound ray bundles 24lll-24l3respectively enter the work piece at three angles. More specifically,the two angles 'y and 8 between the intermediate sound ray bundle 243and the two lateral sound ray bundles 2411, 242 may have either the sameor different values. Thus, for instance,

it is possible to select the angle 'y as an angle of 45and to select theangle 8 as an angle of 60.

The employment of the testing method according to the invention will nowbe explained in connection with FIG. 6 showing the arrangement of twoultrasound heads on a work piece which has a welding seam extending inthe longitudinal direction.

The two ultrasound heads 28, 29 which are located opposite to each otherare on the work piece 17 guided parallel to the welding seam 18 with alongitudinal fault 181 and the two transverse faults 182, 183.

These ultrasound heads are able at different angles to emit the soundray bundles 281-283 and 291293. Of these bundles, the fast ray bundle281 or 291 hits perpendicularly upon the longitudinal axis of thewelding seam, whereas the sound ray bundles 282 and 283; 292, 293 hitthe welding seam 18 at angles 'y and 8 which are between 0and 90. Forinstance, the angle 'y 45between the sound ray bundles 281 and 282, andthe angle 8 60between the sound ray bundles 281 and 283.

The testing method operates in conformity with a plurality ofperiodically repeated cycles and in view of the different paths of thesound ray bundles 281-283; 291293 permits scattering of the tested areasthrough corresponding monitor adjustment on the ultrasound device asillustrated diagrammatically in FIG. 7. The following table will inconnection with two examples illustrate the working manner and sequenceof the cycles:

Emission Reception by Means of With Ultrasound Sound Ray Bundles MonitorOrifice Head 28 29 281/ 282/ 283/ 291/ 292/ 293/ 281' 282 283' 281' 282283' l l x x 3 x x x x ll. 1 x x 2 x x x x 4 x x x x During cycle 1 ofthe Example 1, the ultrasound head 28 operates as emitter and receiver,while the ultrasound head 29 is ineffective. Thus, by means of the soundray bundle 281 through the monitor orifice 281 the welding seam 18 istested for longitudinal faults 181. During the cycle 2, the functions ofthe two ultrasound heads 28 and 29 are exchanged. During the thirdcycle, the ultrasound head 28 emits the sound ray bundles 281, 282, 283in three directions. The ultrasound head 29 now serves as receiver forthe said three sound ray bundles 281/291 and 282 and 283 if they arereflected at transverse faults and reach the ultrasound head 29 in theform of sound ray bundles 292 and 293. Through the intervention of themonitor orifices 281', 282 and 283', the three signals of the threesound ray bundles 281, 282 and 283 are in connection with the sound raybundles 291, 292, 293 received separately from each other. The monitororifice 281', sound ray bundle 281 plus 291 checks the function of theultrasound heads 28, 29 and the coupling thereof to the work piece 17.By corresponding amplifying and/or output control devices, it ispossible in a manner known per se to control the sound level received inthe ultrasound head 29 in conformity with the sound-through orinsonating method so as to adjust said level to a normal value. Thesound ray bundles 281 plus 292 and 283 plus 293 received by the monitororifice 282' and 283 serve as indication of transverse faults 182, 183in the welding seam 18. The time period of the individual cycles may bethe same or may be of different lengths.

Example [I illustrates another one of the numerous combinations of theindividual working cycles inherent to testing function.

For purposes of employing the method according to the invention and thedevice according to the invention, it is to be understood that saidmethod and device are not limited to the destruction-free testing ofwelding seams which have been selected merely by way of example but arealso applicable generally to the testing of sheet metal plates, bands,rods and pipes which are tested by ultrasound energy.

For the sake of completeness it may be added that monitor orifices suchas those designated with the reference numerals 282 283' are known inthe art and described for instance in the publication Werkstoffprufilngmit Ultraschall (Material testing by ultrasound) by J. H. Krautkramer,second edition, published by Springer-Verlag Berlin, Heidelberg, NewYork, page 201 et seq.

It is also to be understood that the present invention is, by no means,limited to the showing in the drawings but also comprises anymodifications within the scope of the appended claims.

What we claim is: l. A method of checking the material of a workpiecealong a linear formation for longitudinal and transverse faults in theheterogeneity of the material which includes the steps of: producingultrasonic vibrations from a single spurge, separating the ultrasonicrays from mrbfifins inteTp tr g ggggjgigiifigf'iil trasonic ray bundles,tr afis'inifting said bundles of rays substantially siiiiultaneously tosaid linear formation with one of said bundles at a right angle to saidlinear formation and another bundle of rays at less than a right angleto said linear formation, andr eceivingand g egg rgi ng t l e raysreflected by said linear formation from each of sai d bundles, so thatreflections of the ray bundle at right angles will indicate longitudinalfaults and reflections from the ray bundle at less than a right anglewill indicate transverse faults.

2. A method according to claim 1, in which aplur all;

Ban les ar lra sm ttsq from m single sources of vibrations positioned onopposite s1 es al formationwith thelgupd lesb fie'ach source directed tosaid longitudinal formation at similar angles, said sources operatingsuccessively so that one source is inactive when the other source istransmitting.

3. A method according to claim 2, in which said ultrasonic ray sourcesare both transmitters and receivers, the inactive transmitter acting asa receiver to actuate a recorder when the other source is transmitting.

4. A method according to claim 1, in which said ultrasonic ray sourcetransmits three ray bundles at angles to each other, two of said bundlesbeing directed to said longitudinal formation at different angles lessthan a right angle.

5. An apparatus for non-destructively checking a workpiece, especially awelding seam, in its longitudinal as well as in its transverse directionas to faults in the heterogenity of the section of the material to bechecked, which includes: only t v vo ultrasonic heads adaptedrespectively to be placed on gppositesides of and substantially adjacentto the material section t o be checked, and respectively associated withsaid heads a'n d operable alternatelytomaintain one of said heads inartiye y hile causing the other head to ssmara'y "Erifrgthe s tothernaterial section to be checked an d to receive sauna" wav ri flected bysaid material section to thereby detect faults in the longitudinal andtransverse direction of the material section to be checked, and monitormeans for recording the reflected sound waves, each of said heads haveonly one ultrasonic vibrator, the ultrasonic vibrator being adaptedrespectively to emit two sound ray bundles to opposite sides of saidvibrator and which includes a body of synthetic material having saidvibrator embedded therein and being adapted to conduct sound, said bodybeing so designed that said two ultrasonic ray bundles are refracted andguided in such a way that they extend through a common coupling surfacein predetermined directions toward the material section to be checked.

6. An apparatus for non-destructively checking a workpiece, especially awelding seam, in its longitudinal as well as in its transverse directionas to faults in the heterogenity of the section of the material to bechecked, which includes: only two ultrasonic heads adapted respectivelyto be placed on opposite sides of and substantially adjacent to thematerial section to be checked, means respectively associated with saidheads and operable alternately to maintain one of said heads inactivewhile causing the other head to send sound ray bundles to the materialsection to be checked and to receive sound waves reflected by saidmaterial section to thereby detect faults in the longitudinal andtransverse direction of the material section to be checked, and monitormeans for recording the reflected sound waves, a unilaterally emittingultrasonic vibrator, and a sound-optical-principle adapter arranged infront of said vibrator, said adapter forming a sound conductingsynthetic body having that side thereof which faces away from saidultrasonic vibrator provided with means defining cuts filled withmaterial which is a poor sound conductor, that side of said syntheticbody which faces the coupling surface extending at an incline from theoutside toward the center.

7. An apparatus according to claim 7, which includes a lead chamberassociated with said adapter and filled with a sound refracting liquid,and sleeve means defining boundary for said chamber.

8. An apparatus according to claim 7, which includes adapter memberarranged in front of said chamber and complementarily shaped inconformity with the surface of the workpiece to be checked.

1. A method of checking the material of a workpiece along a linearformation for longitudinal and transverse faults in the heterogeneity ofthe material which includes the steps of: producing ultrasonicvibrations from a single source, separating the ultrasonic rays fromsaid vibrations into a plurality of distinct ultrasonic ray bundles,transmitting said bundles of rays substantially simultaneously to saidlinear formation with one of said bundles at a right angle to saidlinear formation and another bundle of rays at less than a right angleto said linear formation, and receiving and recording the rays reflectedby said linear formation from each of said bundles, so that reflectionsof the ray bundle at right angles will indicate longitudinal faults andreflections from the ray bundle at less than a right angle will indicatetransverse faults.
 2. A method according to claim 1, in which aplurality of ultrasonic ray bundles are transmitted from each of twosingle sources of vibrations positioned on opposite sides of saidlongitudinal formation with the bundles of each source directed to saidlongitudinal formation at similar angles, said sources operatingsuccessively so that one source is inactive when the other source istransmitting.
 3. A method according to claim 2, in which said ultrasonicray sources are both transmitters and receivers, the inactivetransmitter acting as a receiver to actuate a recorder when the othersource is transmitting.
 4. A method according to claim 1, in which saidultrasonic ray source transmits three ray bundles at angles to eachother, two of said bundles being directed to said longitudinal formationat different angles less than a right angle.
 5. An apparatus fornon-destructively checking a workpiece, especially a welding seam, inits longitudinal as well as in its transverse direction as to faults inthe heterogenity of the section of the material to be checked, whichincludes: only two ultrasonic heads adapted respectively to be placed onopposite sides of and substantially adjacent to the material section tobe checked, means respectively associated with said heads and operablealternately to maintain one of said heads inactive while causing theother head to send sound ray bundles to the material section to bechecked and to receive sound waves reflected by said material section tothereby detect faults in the longitudinal and transverse direction ofthe material section to be checked, and monitor means for recording thereflected sound waves, each of said heads having only one ultrasonicvibrator, the ultrasonic vibrator being adapted respectively to emit twosound ray bundles to opposite sides of said vibrator and which includesa body of synthetic material having said vibrator embedded therein andbeing adapted to conduct sound, said body being so designed that saidtwo ultrasonic ray bundles are refracted and guided in such a way thatthey extend through a common coupling surface in predetermineddirections toward the material section to be checked.
 6. An apparatusfor non-destructively checking a workpiece, especially a welding seam,in its longitudinal as well as in its transverse direction as to faultsin the heterogenity of the section of the material to be checked, whichincludes: only two ultrasonic heads adapted respectively to be placed onopposite sides of and substantially adjacent to the material section tobe checked, means respectively associated with said heads and operablealternately to maintain one of said heads inactive while causing theother head to send sound ray bundles to the material section to bechecked and to receive sound waves reflected by said material section tothereby detect faults in the longitudinal and transverse direction ofthe material section to be checked, and monitor means for recording thereflected sound waves, a unilaterally emitting ultrasonic vibrator, anda sound-optical-principle adapter arranged in front of said vibrator,said adapter forming a sound conducting synthetic body having that sidethereof which faces away from said ultrasonic vibrator provided withmeans defining cuts filled with material which is a poor soundconductor, that side of said synthetic body which faces the couplingsurface extending at an incline from the outside toward the center. 7.An apparatus according to claim 6, which includes a lead chamberassociated with said adapter and filled with a sound refracting liquid,and sleeve means defining boundary for said chamber.
 8. An apparatusaccording to claim 7, which includes adapter member arranged in front ofsaid chamber and complementarily shaped in conformity with the surfaceof the workpiece to be checked.